1. Field of The Invention
The present invention relates to a rolling mill and associated method which is adapted through specifically controlled stages of alteration of workpiece profile and, in certain preferred forms creating shear stresses and minimizing of friction between the work rolls and workpiece to provide an efficient means for rolling a metal workpiece.
2. Description Of The Prior Art
It has been known to provide a metal workpiece of given width through longitudinal slitting of the edges. This approach, however, can result in undesired production of substantial scrap.
It has also been known in connection with rolling of metal slabs to provide an initial profile from the sizing pass wherein the central portion of the slab is of reduced thickness with respect to the generally transversely outwardly diverging lateral portions thereof. Subsequently, the workpiece is rotated 90 degrees and it is run through a rolling millstand which providesa a generally uniform thickness to the workpiece. The workpiece is subsequently rotated 90 degrees in the opposite direction from the initial rotation and further rolling is effect so as to provide a workpiece of desired uniform thickness. This practice is generally known as "broadsiding". One of the difficulties with this practice is the need to effect two 90 degree rotations of the workpiece. See generally U.S. Pat. Nos. 4,238,946 and 4,392,371.
It has also been known in rolling mills to effect axial displacement of rolls. See U.S. Pat. Nos. 4,320,643 and 4,440,012.
It has also been suggested to harden parts by cold rolling by applying a pulsating force to the workpiece. See U.S. Pat. No. 4,327,568.
It has also been suggested to increase the efficiency of rolling by applying pulsating force to the work rolls in vertical and horizontal planes. See generally USSR patents Nos. SU 617 089 and SU 686 794. These systems do not involve use of such concepts for spreading of the workpiece.
In spite of these known practices, there remains a need for a more efficient, more direct method and apparatus for effecting spreading of a metal workpiece during the rolling operation.